A surface inspection apparatus, which inspects the surface of the object under inspection optically, a scattered light detection type or a reflected light detection type, in which the surface of the object under inspection is illuminated by a inspection light and a scattered light or a reflected light from the surface of the object under inspection is detected, is generally known (See Japanese Patent Laid-Open 2001-66263, for example). The scattered light detection type and the reflected light detection type are suitable for measuring shapes, sizes, etc. of the defects on the surface of the object under inspection.
There is also an interference phase detection type, in which a reference surface and the surface of the object under inspection are illuminated by divided inspection lights, and the interference between a reflected light from the reference surface and a reflected light from the surface of the object under inspection is detected (Japanese Patent Laid-Open 2000-121317, for example). The interference phase detection type is suitable for measuring heights, depths, etc. of the defects on the surface of the object under inspection. It is also utilized for measuring thicknesses of semiconductor wafers, etc. (Japanese Patent Laid-Open 2000-234912, for example).
In consideration of differences in the shapes, sizes, optical characters, etc. of the defects, some surface inspection apparatus adopt two or more of the above-mentioned detection methods.
In a surface inspection of a magnetic disk or its substrate, for example, there are various kinds of defects to be detected, such as particles, stains, pits, bumps, dimples, scratches, handling damages, grinds, etc. Although these various defects should be detected and discriminated during the surface inspection, the discrimination accuracy of the defects naturally has some limits when using the above-mentioned optical detection methods only.
Moreover, when foreign matters, such as the particles, stains, etc., are adhering to the surface of the object under inspection, such as the magnetic disk, a semiconductor wafer, a liquid crystal substrate, etc., it is necessary to prove substances of the foreign matters in order to manage production processes. However, it was sometimes difficult to know the substances of the foreign matters from the shapes, sizes, heights, etc., which are measured by the above-mentioned optical detection methods, and detailed analyses are separately needed.